Historically, isotope analysis originated as a major tool for the field of geochemistry. However, as mass spectrometers and other equipment for taking isotopic measurements improve and advance, so does the utility of isotopic data in other areas. These have come to include oil and gas exploration, and gas identification and differentiation. In addition, isotope data has also become a useful tool in other fields, such as ecology, forensics, food adulteration, and others where isotope data can often provide a means of differentiating two otherwise chemically indistinguishable or undifferentiated substances.
As our world's energy supplies diminish, increasing attention is being given to recovering sources of oil and gas that were previously considered uneconomical and/or unconventional. These sources may be identified through “geochemical prospecting” of surface soils. A bag for containing a sample of soil and its associated gases, without altering its isotopic “signature” would be extremely valuable in helping to identify these sources. However, isotopic differences can arise in a sample during storage. Accordingly, it would be beneficial to control for mechanisms that might alter the isotopic signature of a sample substance. Geological sampling often requires specialized sampling containers and equipment, as described in various of the following published US applications: 20100083771 (Gas sampling apparatus); 20090260416 (Low dead-volume core-degassing apparatus); 20080282814 (Gas sampling apparatus); 20070056394 (Pressurized gas sampling container); 20040123679 (Gas sampling apparatus); the disclosures of which are incorporated herein by reference. Such devices can be used to contain a substance without altering or “fractionating” the sample's isotopic signature.
Traditional means of collecting soil samples utilize jars or other rigid containers which are quite bulky and relatively expensive to ship, especially to remote regions of the world where such prospecting often occurs. A rigid container (such as a jar) is always contaminated and/or its contents “diluted” by the atmospheric gases that occupy the container, and which constitute the headspace after the sample is introduced and the container sealed. This gaseous contamination (including atmospherically-borne contaminants) makes subsequent isotopic analysis difficult if not impossible. Additionally, techniques have been developed for sourcing groundwater from core samples using stable isotope analysis. In order to use such techniques, however, it is essential that samples be stored in such a way that prevents isotopic fractionation of the water vapor inside (i.e., no leakage on a molecular level).